Details of Grant 

EPSRC Reference:	GR/R94640/01
Title:	Alignment of Chevron-shaped Molecules Without Aliphatic Tails
Principal Investigator:	Ashwell, Professor G
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Researcher Co-Investigators:
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Department:	Sch of Engineering
Organisation:	Cranfield University
Scheme:	Standard Research (Pre-FEC)
Starts:	01 July 2003	Ends:	30 June 2006	Value (£):	130,107
EPSRC Research Topic Classifications:	Materials Synthesis & Growth
EPSRC Industrial Sector Classifications:
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Summary on Grant Application Form
Organic donor-(pi-bridge)-acceptor dyes have been actively studied for a variety of applications, e.g. second-harmonic generation and molecular rectification, but are difficult to align unless diluted in a polymer matrix and electrically poled or substituted by hydrophobic alkyl tails and deposited by the Langmuir-Blodgett technique. Both methods result in an extensive dilution of the active chromophore units. However, a recent discovery at Cranfield has now identified a new class of optically nonlinear dyes which do not have long hydrophobic alkyl tails yet form non-centrosymmetric films. They have a central cationic acceptor, which is substituted by two pi-bridged donor groups with an angle of ca. 120 degrees between the charge-transfer axes of the chevron-shaped D-pi-(A)-pi-D unit. Studies on two preliminary examples have demonstrated that the molecules readily align at the air-water interface and that the resultant films have high second-order susceptibilities and also exhibit molecular rectification when sandwiched as monolayers between gold electrodes. The nonlinear optical and electrical properties of this new type of film are greatly improved because there is no need for long alkyl tails which, in conventional films, suppress the susceptibility and act as insulating barriers. Based on this discovery the aim is to optimise the design of chevron-shaped molecules to improve the alignment and, therefore, the nonlinear properties.
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Organisation Website:	http://www.cranfield.ac.uk